launchpad: Prevent error due to origin listed twice

launchpadlib can list the last modified repository twice so ensure to yield
a single ListedOrigin model for that special case.

Related to T3003#57551

swh/lister/launchpad/lister.py

@@ -93,12 +93,15 @@ class LaunchpadLister(Lister[LaunchpadListerState, LaunchpadPageType]):
         """
         assert self.lister_obj.id is not None
 
+        prev_origin_url = None
+
         for repo in page:
 
             origin_url = repo.git_https_url
 
-            # filter out origins with invalid URL
-            if not origin_url.startswith("https://"):
+            # filter out origins with invalid URL or origin previously listed
+            # (last modified repository will be listed twice by launchpadlib)
+            if not origin_url.startswith("https://") or origin_url == prev_origin_url:
                 continue
 
             last_update = repo.date_last_modified
@@ -107,6 +110,8 @@ class LaunchpadLister(Lister[LaunchpadListerState, LaunchpadPageType]):
 
             logger.debug("Found origin %s last updated on %s", origin_url, last_update)
 
+            prev_origin_url = origin_url
+
             yield ListedOrigin(
                 lister_id=self.lister_obj.id,
                 visit_type="git",

swh/lister/launchpad/tests/test_lister.py

@@ -154,3 +154,22 @@ def test_launchpad_lister_invalid_url_filtering(
     assert not lister.updated
     assert stats.pages == 1
     assert stats.origins == 0
+
+
+def test_launchpad_lister_duplicated_origin(
+    swh_scheduler, mocker,
+):
+    origin = _Repo(
+        {
+            "git_https_url": "https://git.launchpad.net/test",
+            "date_last_modified": "2021-01-14 21:05:31.231406+00:00",
+        }
+    )
+    origins = [origin, origin]
+    _mock_getRepositories(mocker, origins)
+    lister = LaunchpadLister(scheduler=swh_scheduler)
+    stats = lister.run()
+
+    assert lister.updated
+    assert stats.pages == 1
+    assert stats.origins == 1